Frequency

What It Is

How many sessions you divide your weekly training across.

Why It Matters

The evidence suggests that lifting on at least two days a week builds more strength than lifting on one, and that floor is as far as the frequency research reliably reaches. Above it the picture flattens. The major syntheses decline to name a dose-response, the useful upper limit is undetermined, and the direct comparisons between training twice a week and training more often show little to no difference in the strength and muscle you gain.

Frequency works mostly by carrying volume. Once weekly sets are matched, training a muscle on one day or on five makes little to no difference to how much it grows, and the strength advantage that higher frequencies show in raw comparisons shrinks when the sets are equalized. The instruction to train every muscle group twice a week comes from an early meta-analysis; when much of the same group repeated it on a far larger set of trials, the difference did not hold. What does survive is a strength benefit concentrated in the step from one session to two. It turns up on the lifts people are tested on rather than in muscle size, so practice at the movement may account for much of it.

So choose the number of sessions that lets you accumulate your weekly volume without letting set quality slide, and treat two as a floor rather than a target. Two full-body sessions, three, or a four-day split all work if the weekly sets land. In adults over 60, each added day has been found to bring a little more strength and no extra muscle.

• Grgic, J. et al. (2018). Effect of Resistance Training Frequency on Gains in Muscular Strength: A Systematic Review and Meta-Analysis. Sports Medicine. doi.org/10.1007/s40279-018-0872-x
• Ralston, G.W. et al. (2018). Weekly Training Frequency Effects on Strength Gain: A Meta-Analysis. Sports Medicine - Open. doi.org/10.1186/s40798-018-0149-9
• Schoenfeld, B.J. et al. (2019). How many times per week should a muscle be trained to maximize muscle hypertrophy? A systematic review and meta-analysis of studies examining the effects of resistance training frequency. Journal of Sports Sciences. doi.org/10.1080/02640414.2018.1555906
• Kneffel, Z. et al. (2021). A meta-regression of the effects of resistance training frequency on muscular strength and hypertrophy in adults over 60 years of age. Journal of Sports Sciences. doi.org/10.1080/02640414.2020.1822595
• Currier, B.S. et al. (2023). Resistance training prescription for muscle strength and hypertrophy in healthy adults: a systematic review and Bayesian network meta-analysis. British Journal of Sports Medicine. doi.org/10.1136/bjsports-2023-106807
• Pelland, J.C. et al. (2025). The Resistance Training Dose Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gains. Sports Medicine. doi.org/10.1007/s40279-025-02344-w
• Currier, B.S. et al. (2026). American College of Sports Medicine Position Stand. Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy Adults: An Overview of Reviews. Medicine & Science in Sports & Exercise. doi.org/10.1249/MSS.0000000000003897